C2.2 Neural Signalling

Central Nervous System (CNS)

Part of the nervous system consisting of the brain and spinal cord

Peripheral Nervous System (PNS)

The sensory and motor neurons that connect the CNS to the rest of the body.

Neuron

A specialized cell (nerve cell) transmitting information as electrical (nerve) impulses throughout the body

Dendrites

Branchlike parts of a neuron that have a large SA to receive information.

Axon

A threadlike extension of a neuron that carries nerve impulses away from the cell body. Covered in Schwann cells producing myelinated sheath.

Myelinated Sheath

covers the axon of some neurons and helps speed neural impulses

Nodes of Ranvier

Gaps in the myelin sheath to which voltage-gated sodium channels are confined.

Resting potential/potential difference

The difference in electric charge between the inside and outside of a neuron's cell membrane

Nerve impulse

A signal transmitted along a nerve fiber.

Action potential

The change in electrical potential causing a rapid electrical signal to travel along a nerve fibre. Result of temporary change of electrical potential (polarity) in neuron membrane.

Propogation

movement of an action potential along the length of an axon

Nerve conduction velocity

Speed at which an impulse travels through a nerve

Synapse

Junction between two neurons or a neuron and an effector cell.

Synaptic transmission

The relaying of information from one neuron to a receptor cell/neuron across the synapse by means of neurotransmitters.

Neuromuscular junction

Junction between a motor neuron and a muscle fibre

Presynaptic (axon) terminal

Located at the end of the presynaptic neuron. It is where action potential (electric signal) is converted into chemical signal (neurotransmitter release).

Presynaptic neuron

conducts impulses toward the synapse

Neurotransmitter

Chemical messengers between neurons.

Presynaptic membrane

Specialized membrane of the axon terminal of the presynaptic neuron.

Synaptic cleft

The narrow gap that separates the presynaptic neuron from the postsynaptic cell/neuron.

Threshold potential

The minimum membrane potential that must be reached in order for an action potential to be generated.

Excitatory postsynaptic potential (EPSP)

A slight depolarization of a postsynaptic cell, enhancing the likelihood of an action potential

Acetylcholine (ACh)

Most common neurotransmitter (also in neuromuscular junctions). Small molecule.

Acetylcholinesterase

Enzyme that breaks down acetylcholine in synaptic cleft